QtCreator - working with third party libraries best practices [multi-platform]

I'm relatively new to C++ so maybe that's the problem. Basically, I am working a small purpose-built media player and I'd like to use http://taglib.github.io/ to get at the metadata of all my media files, and as time goes on I'm pretty certain I'll want to use other libraries as well for various things.

I am currently developing on windows (my target audience) but I chose Qt specifically so that I can support multiple platforms.

So initially, I had just unzipped taglib, added the root source folder to my INCLUDEPATH in my pro file. While this allows the IDE to find all the header files, it won't compile as the compiler complains that it cna't find them.

So what is the best practice here, especially knowing that I will want to compile the same project in several different environments?